Infrared and laser Raman gas spectra of SiH4 and SiD4

The ν₂(e) and ν₃(f₂) Raman spectra have been examined. For ²⁸SiH₄ the ν₂(e) and ν₄(f₂) infrared bands are partly analyzed and compared with a computed band-contour; the ν₁ + ν₃ combination infrared band has been presented. For ²⁸SiH₄ the 2ν₃ overtone infrared band has been observed and analyzed. The new data are combined with those of the ν₃(f₂) infrared bands to derive an improved set of rovibrational constants of ²⁸SiH₄ and ²⁸SiD₄. The analyses yield $\text{r}{}_0\text{= 1.4806 ± 0.0008}\text{A}\text{?}$ for ²⁸SiH₄ and $\text{r}{}_0\text{= 1.4784 ± 0.0006}\text{A}\text{?}$ for ²⁸SiD₄ in agreement with the Laurie-Herschbach theorem.